Sudsing profile is important for a cleaning composition, particularly laundry detergent, where the appropriate volume and speed of suds formation, retention and dissolution in the wash and rinse cycles are considered key benchmarks of performance by the consumers. For laundry detergents, while a sudsing profile is important for machine washing process, it is even more important in a typical hand-washing process as the consumer would see changes in the suds level in the wash and rinse cycles. Typically, consumers, particularly hand-washing consumers, desire laundry detergent that dissolves in the wash liquor to give voluminous suds during the wash cycle to signify sufficient performance. The suds are then carried over to the rinse solution and require additional time, water and labor to thoroughly rinse from the laundered fabric.
However, reducing the suds level overall is not a viable option because when the consumer sees little or no suds during the washing cycle, it causes the consumer to believe that the laundry detergent is not as active. In addition, the current market demands are for laundry detergents with improved environmental sustainability (e.g., less water consumption) without negatively impacting cleaning performance or the perception of cleaning performance (i.e., appearance of suds on fabric or in the rinse solution). This, of course, reinforces the preference for laundry detergents having improved foam control composition for faster suds dissolution during the rinse cycle so as to reduce extra rinse cycles needed to remove the suds from the cleaned fabrics/rinse solution. Thus, there is a need for a cleaning composition having a sudsing profile where there is strong level of suds volume during the washing cycle, and yet quickly collapses in the rinsing solution for substantially reduced or zero suds for cost savings and environmental conservation purposes. This is known as the “single rinse” concept.
One solution has been to add a de-foaming agent during the rinse cycles, but this option is cost prohibitive for most hand-washing consumers. Additionally, the prior art discloses laundry detergent compositions with various foam-control or anti-foaming agents in an attempt to address this problem. For example, PCT Publication No. WO2011/107397 (Unilever) discloses a laundry detergent composition comprising a delayed-release amino-silicone based anti-foaming agent that is absorbed onto a carrier or filler to act in the rinsing cycle to reduce or eliminate suds, preferably after two rinse cycles. However, the suds control benefit imparted by such amino-silicone based anti-foaming agent may still come at the expense of wash suds, i.e., the wash suds volume can be significantly reduced since the silicone release timing is difficult to control. Inopportune release of the silicone anti-foam may lead to significant reduction of wash suds volume, which will give consumer the impression that the detergent composition contains lower surfactant level and is therefore of lower quality/value. EP Publication No. EP0685250A1 (Dow Corning) discloses a foam control composition for use in laundry detergents that inhibits the formation of new suds during the post-wash rinsing cycles, but which does not appear to quicken the elimination of already existing suds carried over from the wash cycle.
Accordingly, there is a need for a cleaning composition, preferably a laundry detergent composition, which enables strong suds formation (both fast generation of large volume of suds as well as stability or sustainability of the suds already generated over time) during the wash cycle while reducing and eliminating the suds quickly during the rinse cycle(s), preferably across a range of consumer wash habits and fabric/material surfaces being washed, so that a single rinse cycle might be sufficient to remove the suds, thereby enabling the “single rinse” concept.
Further, conventional de-foaming or anti-foaming agents, especially the polymeric de-foaming or anti-foaming agents, are known to cause significant whiteness loss in fabrics after repeated wash cycles, i.e., the grey or dull color in fabrics that have been exposed to many wash cycles. Therefore, the usage of such polymeric de-foaming or anti-foaming agents has been limited in laundry detergent compositions. Correspondingly, it will be an advantage for laundry detergent compositions to also have reduced whiteness loss in fabrics after repeated wash.